Ok, so I spent the last hour looking at all the 508 oil manufactures specs I could find. Not a single oil manufacture mentions anything about the dye being able to be used to find leaks, and all of them say it's green to "differentiate" it from other oils. I also PM'd 2 different VW techs that belong to our local club. They say they haven't heard of or been trained in using the green dye in 508 to find leaks. There is specific florescent dye that they can add, but to their knowledge, the 508 dye isn't florescent. And if it is, and you wanted to fool the dealer, you could go to autozone and add some dye to whatever oil you run.
Here's one of the many brands of dye.
https://www.denlorstools.com/autobl...leak,be traced much easier back to the source.
But lets get back to basics. If your car calls for 508, you should run 508, unless you track the car. If you track the car, depending on the length of sessions, region you live, and how hard you drive, you should run a higher weight oil, because the types of heat you see in the mk7 on track will destroy 0w-20.